The present invention generally relates to welding equipment and, more specifically, to autogenous portable welding apparatus.
While numerous gaseous fuels are used for welding and brazing, high temperature welding and cutting operations invariably require mixtures of gaseous fuels with oxygen. Since oxygen is typically supplied from high pressure cylinders, such welding systems are seldom portable or easily transportable because of the generally large sizes and heavy weights of the high pressure oxygen cylinders.
Small units have been developed to accommodate the needs of artisans in the field and hobbyists. Some of thee units have been described as autogenous because, during operation, they are self-sustaining and provide both the gaseous fuel as well as oxygen, which is self-generated.
Autogenous units typically use a low pressure source of combustible gas such as butane or propane cartridges. However, these units in addition, incorporate a small oxygen generating plant which typically decomposes hydrogen peroxide. For example, in U.S. Pat. No. 4,308,235, a portable welding apparatus is described for welding by means of an oxygen-gas flame. However, since the oxygen generator yields low pressure oxygen, the method used for increasing the pressure of the oxygen to a level compatible with the fuel delivery pressure is to connect the fuel supply to the oxygen generator. However, such a system is not truly autogenous since the pressurization of the system depends on an external source such as from a pump, a pressure cylinder or, as noted, a gas source. Where a gas source is used, the use of a combustible gas to pressurize the hydrogen peroxide creates a potentially hazardous condition. Thus, while such units have been known, they have not achieved commercial success because of their complexity and inconvenience of use and as a result of their defects in both operation and in safety of use.